For the home plating specialist

[Wilf]

3 VDC @ 500 mA should be a safe bet.

Wilf

[conbs]

I haven't actually tried this yet, but am getting very close. I have read a ton of material on plating. I have not been able to find much on using a vinegar bath, but there is a little bit out there, mostly geared toward science experiments as opposed to trying to actually plate an item for a specific use.

While about any low voltage DC current will cause plating to result, the short answer is that 1.5V should be about right and not over 3V and you want to vary the amps depending on the size of the piece you are plating. Looks like the target should be 100 milliamps per square inch of surface to be plated.

I purchased 4 different books on plating plus read a bunch of info on line. Pretty interesting stuff, but at this point just so much theory. I got sidetracked with a couple of other projects, but will be trying it out soon. BTW after reading up on it, I am not at all afraid to try copper, nickle and even chrome plating. I don't know when I will try it, but you can put together the right set up and purchase the right supplies without too great of expense if you shop smart. A word of caution: if you ever plate anything and get money for it you are a commercial plater and the EPA regs apply to your once private life. Don't do it unless you are sure you want to be in the business and have lifetime responsibility for every chemical you touch. But, you can hobby plate until your heart is content.

[Wilf]

Rock160,

Just to avoid possible confusion about the difference between the numbers conbs and I have given, I will try to explain my suggestion.

Conbs is correct. Zinc plating will occur with 1.5 V DC, and the 100 mA current per square inch is a good number for effective plating. A 3 VDC charger will work just fine (I have used mine for several years now) and they are easy to find. If you need to reduce the voltage for some reason, you can always add a silicon diode or two in series to the circuit.

The 500 mA current rating gives you the ability to plate more surface area, and also provides a bit of a safety factor--the transformer won't be as likely to melt on you, but it is a good idea to check it periodically to make sure it's not heating up too much.

You could also use D cell batteries (preferably rechargeable).

Wilf

[Snakeoil]

Hi guys. I've been away from the forum for a bit. Been monkeying with a couple British bikes.

I started replating some Triumph engine bits yesterday and came over here to find the thread so I could post a link on the Triumphrat forum. You always get "how do I do what you are doing?" questions when you post plating results so much easier to send them here.

To respond to the question regarding the size of the charger to use, I've used a smaller, 5VDC I believe, but I fried it because I pushed the current limit. Since then I found an old charger for a modem that is 12VDC and 1 amp rated. I put an Ohmite rheostat in the circuit to control the current. I'm sure I've described this same set-up here in early posts when I was plating every day during the winter.

Like I said, I control the current, usually. I say usually because with very small parts, the current is also small so in that case, I adjust to keep the voltage at or slightly below 1.5VDC. When doing big parts, I control the current to below 1 amp and let the voltage float to where it wants to be. It is always below 1.5VDC in such a case.

I also run a small fan on my charger to help it reject heat.

regards,
Rob

[Snakeoil]

Got a PM on this subject so I thought I'd post my reply so all can benefit. And perhaps Wilf or G-man can make a suggestion regarding his rheostat problem. I realize it is a rating thing, but not sure why he burned his out and mine just gets warm. Could be mine is very old stock and more robust in nature. But in reading Adam's post again now as I type this, I remember that my choice for the rheostat I have was based on it's wattage. Mine is a 25w unit so at 12vdc, that's 2 amps. So, now I'm really puzzled why his burned out.

Here is the PM exchange.

Hey Snake:

I have just set up a home plating station based on your description. This is what I am using:

12v 1.5amp wall charger
Ohmite 25w 500ohm .22amp Rheostat

Things were working ok, slow but ok with one or two small parts at .300amp. But I burnt out my rheostat when adding parts and increasing amps. What model ohmite rheostat are you using. I see the one that I have is rated to .22amp and this is less than the recommended .300 amp needed for best plating and much less if you want to decrease time by cranking it to just under 1amp for large parts. In your post you deccribe going to slightly below 1.5v for small parts, this puts me way higher than .22amp rated for the rheostat. How are you using this high amp output and not burning rheostats?

I have been looking at ohmite rheostats and the 500ohm 50w only goes to .316amp

I need help picking a rheostat that will work with my wall charger.

Thanks Man and thanks for the detailed descriptions in the posts. It has got me real close to having the perfect plating setup just need a little more help.

Adam



Adam,

First, these types of questions are always best asked in the thread for the subject at hand. That way everyone benefits from the additional input.

I never bothered to look at the rating for my rheostat. I went to a local electronics supply house and told the guy what I wanted and he handed it to me. It was military or some other type of surplus he had purchased and was dirt cheap. New in the box, too.

I just went down to look and it is rated as is yours at 0.22 amps. So, I don't know what to tell you. It does get pretty warm, but so far no signs of overheating.

I've since backed down on my voltage since I've made a new batch of plating bath. I consistently run below 1vdc now and amps are always below 1 amp due to my power supply.

You could check on line with somebody like Newark Supply for a better rheostat. Wilf or G-man might have suggestions if you post your inquiry in the original thread.

regards,
Rob

[NBD925]

I'm so confused. I seemed to think that I had a small command of the electronic subject but it has all been dashed against the rocks.

I have a 12v 1.5amp wall charger. What Rheostat do I need to get, in order to safely put about 1amp current to the parts.

According to the Ohmite selection manual page two, rheostats are selected based on current rating.

http://www.ohmite.com/catalog/pdf/rheostats203.pdf

Based on this I estimated the total current draw at 1.5amp for the wall charger + 1amp for the bleeder current for a total of 2.5amp. I rounded to 3amp to be safe.

The reason I chose this method of calculating my rheostat current rating is because I have the rheostat connected with 12v to the first post and the output connected to the wiper (middle post) and nothing connected to the third post. Is this correct?

Now based on this information if you look at the ohmite rheostats offered and there amp ratings, you have to find one that offers over 3amp capability. I selected 100ohm as a minimum because this would start me at about .12amp for the low end of plating. (12v/100ohm = .120amp)

Here is an OHM's Law calculator:

http://www.ohmite.com/cgi-bin/showpage. ... ers_molded

So looking in this category you end up with the 100ohm 1000w rheostat in the ohmite list.

Here is the Ohmite rheostat list: Scroll down until you get to the amp values section (It's the all grey list at the bottom of the page).

http://www.ohmite.com/catalog/pdf/rheos ... ewound.pdf

Am I wrong here? I could be way off but it made sense to me.

[Snakeoil]

Maybe one of the other guys here with a better background for electric circuits can comment. I'd never heard of bleeder current until I read that write up you posted from Ohmite.

If your charger makes 1.5 amps at full load, then if you exceed that, you are going to burn up your charger. The charger cannot make more amps than it is rated for and survive.

For me it was a simple calc.
You have voltage out of your charger which is 12 vdc. You have 1.5 amp max current, which I would never exceed while plating. 12v x 1.5 a = 18 watts. So you need a rheostat that is rated at least for 18 watts at 12 volts. Higher is better.

My rheostat is a type K, wire round rheostat. It has a ceramic insulation around which the wire is wound. Your last link shows the model K rheostat. Yeah, it's way bigger than I need from a resistance perspective. But the price was right and I'll never burn it out with my little 1 amp charger.

regards,
Rob